Lifting jack



A. C. HOPKINS June 5,1928;

LIF'I'ING JACK Filed April 1, 1927 2 Shoots-Sheet 1 INVENTOR Patented June 5, 1928.

umrsn STATES ARiTI-IUB C. HOPKINS, F NILES MICHIGAN, ASSIGNOR TO NATIONAL-STANDARD COI- PANY, OF NILES, MICHIGAN.

LIFTING JACK.

Application m April 1,

The main object of this invention is to provide an improved. reversing mechanism for lifting jacks of the rack and pawl type.

A. further object is to provide an improved reversing mechanism for lifting jacks of the class described which is positive in operation and simple and durable.

Objects pertaining to detailsand ec.ono mie's of my invention will appear from the description to follow. .The invention is pointed out in the claims.

- A structure embodying the features of my invention is clearly illustrated in the accompanying drawing forminga part of this application, inv which: a

Fig. 1 is a side view of a lifting jack embodying the features of my invention, one -of the side plates of the; standard being partially broken away to disclose the ar-f 2o rangement of the parts within and the reversing member being in inoperative position.

Fig. 2 is a detail vertical section on line 2-2 of Figs. 1 and 3. c

Fig. 3 is a horizontal section on line 33 of Figs. 1 and 2.

Fig. l is a fragmentary side elevation of the jack with the reversing mechanism adjusted to inoperative positionor in position for raising the rack bar.

Fig. 5 is a fragmentary side View with the reversing mechanism in operative position with the holding pawl disengaged. 4

Fig. 6 is a fragmentary view corresponding to that of Fig. 5 with the lifting pawl disengaged.

Fig. 7 is a perspective view of the holding pawl and its actuating spring.

In the embodiment of my improved jack illustrated the structure comprises a standard 1 provided with a suitable base and adapted to receive a lifting bar 2 which is provided with a rack 3. The actuating lever 4 is pivoted at 5.

The lifting pawl 6 is mountedon the pivot 7 on the inner end of the lever 4. The holding pawl 8 is mounted on the pivot 9 0n the frame to coact with the rack. This general arrangement is well known in jacks of this type.

The holding pawl is provided with a spring 10 urging it to rack engaging position while the lifting pawl is provided with a similar spring 11. The pawls are provided with laterally projecting pin-like lugs 12.

The reversing member 13 is pivoted at 14,

1927. Serial No. 180,19

the pivot being located between the lifting and holding pawls. The reversing member has oppositely projecting fingers 15 and 1,6 coacting with the lugs 12. The reversing member has. an Ashaped cam projection 17 disposed centrally relative to the. pivotv 14 and coacting with the reversing member actuating spring 18 which. has an A-shaped cam projection 19 at its endcoacting with the projection 17. The cam 20 pivoted on the frame and havlng a. finger piece 21, is provided for holding thespring 18in inoperative position. The link 22 is mounted on the pivot 7 and provided with a slot 23 engaging a pin 24 promoting from the reversing member, thereby providing a lost motion connection for the lever 4 to the reversing member.

Thus arranged, with the spring 181eleasedv as shown in Figs. 5 and 6. the upstroke of the lever carries the reversing -member downwardly until the apex. of its cam projection passes the apex of the cam on the spring when. the spring acts to actuate the reversing member with a snap action, the lost motion connection between the link and the reversing member permitting such snap action. Also, the lifting member has at that point released the load from the lifting pawL On. the downward stroke of the lever this action is reversed, the holding pawl being thrown out of engagement with the rack.

I My improved reversing mechanism is very positive in its action, is easily thrown into and out of operation and is not likely to be broken or become inoperative. The parts are all housed within a standard excepting the projecting finger piece 21.

I have illustrated and described my im provements in an embodiment which I regard as very practical. I have not attempted to illustrate or describe certain modifications or adaptations which I contemplate as it is believed that this disclosure will enable those skilled in the art to embody or adapt my improvements as may be desired.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. In a lifting jack, the combination of a standard, an actuating lever pivotally mounted on said standard, a rack bar, a lifting pawl pivotally mounted on said actuating lever, a holding pawl pivotally mounted on said standard, said pawls being provided wit-h laterally plOjecting lugs and with springs urging them to rack engaging position, a reversing member pivotally mounted on said standard between said pawls and provided with oppositely disposed lug engaging fingers and with centrally disposed A-sha-ped cam projection, a link pivotally mounted on said lever and having pin and slot connection with said reversing member, an actuating spring for said reversing member mounted on said standard and provided with a cam projection coacting with said cam projection of said reversing member to actuate the reversing member to pawl releasing position after partial actuation through its connection to said lever, and means for holding said actuating spring in inoperative position. I

21111 a lifting jack, the combination of a standard, an actuating lever pivotally mounted on said standard, a rack bar, a lifting pawl pivotally mounted on said ac tuating lever, a holding pawl pivotally mounted on said standard, said pawls being provided with laterally projecting lugs and with springs urging them to rack engaging position, a reversing member pivotally mounted on said standard between said pawls and provided with oppositely disposed lug engaging fingers and with a centrally disposed cam projection a link pivotally mounted on said levervand having pin and slot connection with said reversing member, an actuating spring for said reversing member mounted on said standard to coact with said cam projection of said reversing member to actuate the reversing member to pawl releasing position after partial actuation through its said connection to said lever, and means for holding said actuating spring in inoperative position.

3. In a lifting jack, the combination of a standard, an actuating lever pivotally mounted on said standard, a rack bar, a lifting pawl pivotally mounted on said actuating lever, a holding pawl pivotally mounted on said standard, said pawls being pro- 'v-ided with engaging springs, a reversing member pivotally mounted on said standard between said pawls and provided with oppositely disposed pawl engaging parts and with a centrally disposed cam projection, a reversing member actuating spring mounted on said standard and coacting with said cam projection of said reversing member to actuate the same in both directions from a central position, a link pivotally mounted on said lever and having a lost motion connection with said reversing member-,and means for holding said reversing member actuating spring in inoperative position.

4. In a lifting jack, the combination of a standard, an actuating lever pivotally mounted on said standard, a rack bar, a lift- I ing pawl pivotally mounted on said actuating lever, a holding pawl pivotally mounted on said standard, said pawls being provided with rack engaging springs, a reversing member pivotally mounted on said standard to coact with both of said pawls, a reversing member actuating spring mounted on said standard and coacting with saidcam projection of said reversing member to actuate the same in both directions from a central position, a link pivotally mounted on said lever and having a lost motion connection with said reversing member, and means for holding said reversing member actuating spring in inoperative position.

5. In a lifting jack, the combination of a standard, an actuating lever pivotally mounted on said standard, a rack bar, a lifting pawl plvotally mounted on said actuating lever, a holding pawl pivotally mounted on said standard, said pawls being provided 1 with engaging springs, a reversing member pivotally mounted on said standard to coact with both of said pawls, an actuating member springoperatively associated with said reversing member to actuate the same with a snap action, and a link pivotally mounted on said lever and having a lost motion connection with said reversing member.

6. In a lifting jack, the combination of a standard, an actuating lever pivotally mounted on said standard, a rack bar, a lifting pawl pivotally mounted on said actuating lever, a holding pawl pivotally mounted on said standard, saidpawls being provided with engaging springs, a reversing member pivotally mounted on said standard to coact with both of said pawls, an actuating spring operatively associated with said reversing member to actuate the same with a snap action, and a lost motion connection v for said actuating lever to said reversing member whereby the reversing member is shifted on the actuation of said lever to the position for complete actuation by said spring.

In witness whereof I have hereuntoset my hand.

ARTHUR C. HOPKINS. 

